JP2012202430A - Piston ring and piston structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of shock by preventing an increase in rod acceleration.SOLUTION: This piston ring 10 is wound around a piston body 3 which is housed in a cylinder body 1 storing hydraulic fluid and which partitions a rod-side chamber R1 from a piston-side chamber R2 in the cylinder body 1. The piston ring has an outer peripheral surface 11 in a peripheral direction made to slidably contact with the inner peripheral surface of the cylinder body 1. The outer peripheral surface 11 has a plurality of grooves 12 provided at optional intervals in the peripheral direction, opened, and opposed to the inner peripheral surface of the cylinder body 1. The plurality of grooves 12 are formed in a direction along the axis direction of the cylinder body 1 or a direction inclined to the axis direction of the cylinder body 1, and communicate with one of the rod-side chamber R1 and the piston-side chamber R2.

Description

  The present invention relates to a piston ring and a piston structure, and more particularly to a piston ring wound around a piston body in a cylinder body in a hydraulic shock absorber and an improvement of a piston structure having the piston ring.

  As piston rings wound around the piston body in the cylinder body of the hydraulic shock absorber, there have been various proposals so far, and many of them are, for example, a joint (joint) as disclosed in Patent Document 1. It is composed of a cut type having an end and an endless type having no joint.

  In any of these types, the piston ring slidably contacts the outer peripheral surface with the inner peripheral surface of the cylinder body while being wound around the piston body housed in the cylinder body.

  Therefore, the piston body accommodated in the cylinder body separates the rod side chamber which is one chamber and the piston side chamber which is the other chamber in the cylinder body via the piston ring, and at the distal end portion of the rod body which is inserted into the cylinder body. When the rod body is held and moved in and out of the cylinder body, it slides in the cylinder body via the piston ring.

  That is, the piston ring ensures so-called slidability between the piston body and the cylinder body, and also guarantees so-called sealing performance between the piston body and the cylinder body.

Japanese Patent Laid-Open No. 2008-075668

  As described above, the piston ring is optimal when ensuring both slidability and sealing performance. For example, in a hydraulic shock absorber mounted on a vehicle, the piston ring seal If the performance is lowered, it will lead to a problem that the setting attenuation action is not performed.

  Therefore, in a hydraulic shock absorber mounted on a vehicle, the sealing performance of the piston ring wound around the piston body tends to be emphasized.

  When the sealing performance in the piston ring is regarded as important, the cylinder body of the piston ring may be switched from dynamic friction to static friction, for example, when the hydraulic shock absorber reverses from contraction operation to extension operation or vice versa. The sliding resistance with respect to increases.

  For this reason, when the hydraulic shock absorber is reversed from the contracted state to the extended state or vice versa, the rod acceleration in the hydraulic shock absorber increases as the sliding resistance of the piston ring increases.

  As a result, an impact is generated by increasing the rod acceleration, and this impact leads to a problem of sound generation on the vehicle body side.

  The present invention was devised in view of the above-described situation, and is a hydraulic shock absorber mounted on a vehicle, and a piston ring that does not generate an impact by not increasing the rod acceleration and the winding of the piston ring. An object of the present invention is to provide a piston structure.

  In order to achieve the above-described object, the structure of the piston ring according to the present invention is housed in a cylinder body that contains hydraulic oil, and is wound around a piston body that separates a rod side chamber and a piston side chamber. The piston ring has a circumferential outer circumferential surface that is in sliding contact with the inner circumferential surface of the cylinder body, and the outer circumferential surface is opened at an arbitrary interval in the circumferential direction and faces the inner circumferential surface of the cylinder body. The plurality of grooves are formed in a direction along the axial direction of the cylinder body or in a direction inclined with respect to the axial direction of the cylinder body, and are formed in the rod side chamber and the piston side chamber. It is assumed that it is communicated with either one.

  The structure of the piston structure according to the present invention includes a piston body that is housed in a cylinder body that accommodates hydraulic oil and separates a rod side chamber and a piston side chamber in the cylinder body, and a piston that is wound around the piston body. In the piston structure including the ring, the piston ring has a circumferential outer peripheral surface that is in sliding contact with the inner peripheral surface of the cylinder body, and the outer peripheral surface is provided at an arbitrary interval in the circumferential direction. A plurality of grooves that open and face the inner peripheral surface of the cylinder body, the plurality of grooves being inclined in a direction along the axial direction of the cylinder body or with respect to the axial direction of the cylinder body And is connected to either the rod side chamber or the piston side chamber.

  Therefore, in the piston ring and the piston structure having the piston ring according to the present invention, the plurality of grooves opened on the outer peripheral surface of the piston ring allow the hydraulic oil contained in the cylinder body to enter and enter the groove. The working oil forms a lubricating film between the outer peripheral surface of the piston ring and the inner peripheral surface of the cylinder body that is in sliding contact with the outer peripheral surface.

  Therefore, even if the outer peripheral surface of the piston ring formed on the so-called smooth surface comes into sliding contact with the inner peripheral surface of the opposing cylinder body, the lubricating film formed between the two is not removed. Reduce the sliding resistance against the cylinder body.

  Therefore, when the hydraulic shock absorber reverses from the contracted state to the extended state or vice versa, the rod acceleration in the hydraulic shock absorber does not increase as much as the sliding resistance of the piston ring with respect to the cylinder body decreases.

  As a result, according to the piston ring of the present invention and the piston structure having the piston ring, in the hydraulic shock absorber mounted on the vehicle, it is possible to prevent the occurrence of an impact by not increasing the rod acceleration.

It is a fragmentary longitudinal cross-section which shows a hydraulic shock absorber provided with the piston structure by one Embodiment of this invention. It is a perspective view which shows the piston ring by one Embodiment of this invention. FIG. 3 is a top view of the piston ring shown in FIG. 2. It is a partial front view which expand | deploys and shows the outer peripheral surface of a piston ring. (A), (B) and (C) are partial views showing the upper end surface of the piston ring in an enlarged manner, and (D) and (E) are piston rings shown at the XX line position in (A). FIG.

  The present invention will be described below based on the illustrated embodiments. As shown in FIG. 1, a hydraulic shock absorber having a piston structure according to an embodiment of the present invention includes a cylinder body 1, a rod body 2, and a piston body 3. The piston body 3 is in accordance with the present invention. A piston structure around which the piston ring 10 is wound is configured.

  In the figure, the hydraulic shock absorber is formed in a single cylinder type. However, from the point of the present invention, the hydraulic shock absorber may be formed in a double cylinder type.

  The cylinder body 1 is in the illustrated hydraulic shock absorber and is a lower end side member, for example, connected to the axle side of the vehicle, and contains hydraulic oil inside.

  In the cylinder body 1, a lower end opening (not shown) is closed with, for example, a bottom cap, and the bottom cap has a mounting bracket such as an eye that enables connection to the axle side of the vehicle.

  Further, in the cylinder body 1, an upper end opening (not shown) is closed by, for example, a rod guide and a head cap, and the rod guide and the head cap allow the rod body 2 to pass through the shaft core portion so as to freely enter and exit.

  The rod body 2 is an upper end side member in the hydraulic shock absorber, and can be connected to the vehicle body side of the vehicle, for example. Therefore, although not shown, the vehicle body side or mount in the vehicle is connected. An upper end thread portion is provided, and a distal end side portion which is a lower end side portion is inserted into the cylinder body 1 so as to be freely inserted and removed.

  The rod body 2 is inserted into the cylinder body 1 so that the tip side (not shown) which is the lower end side in FIG. The piston body 3 is held at the tip 2a which is the lower end.

  The piston body 3 is formed in an annular shape and is freely accommodated in the cylinder body 1 so as to move along the axial direction of the cylinder body 1, and is attached to the distal end portion 2 a of the rod body 2 penetrating the shaft core portion. The rod side chamber R1 that is held and the rod body 2 that is one chamber in the cylinder body 1 inserts the shaft core portion, and the piston side chamber R2 that the rod body 2 that is the other chamber does not pass the shaft core portion is separated.

  The piston body 3 has a passage allowing the communication between the rod side chamber R1 and the piston side chamber R2 in the cylinder body 1, that is, an outer passage 3a. The downstream side which is the upper end of the outer passage 3a in the drawing. The back valve 31 is closed so that the end can be opened.

  The illustrated piston body 3 has a damping valve 32 stacked therein, and this damping valve 32 is arranged in parallel with the outer passage 3a to allow communication between the rod side chamber R1 and the piston side chamber R2 (not shown). The downstream end which is the lower end in the figure of FIG.

  The piston body 3 is wound in a state where the piston ring 10 according to the present invention is housed in an annular groove (not shown) formed in the outer peripheral portion (not shown). A sealing property that prevents so-called leakage of hydraulic oil between the piston body 3 and the cylinder body 1 is ensured, and a so-called sliding property of the piston body 3 with respect to the cylinder body 1 is ensured.

  Note that, in the illustrated hydraulic shock absorber, the piston structure according to the present invention having the above-described piston body 3 includes a step portion 2b which is a boundary portion between the distal end portion 2a of the rod body 2 and a shaft portion (not shown), It is sandwiched between a piston nut 21 that is screwed to a tip thread portion (not shown) of the rod body 2.

  In other words, the piston structure has a valve stopper 33, a back valve 31, a piston body 3, a damping valve 32, and a valve stopper 34 that are stacked, and is sandwiched between the step 2 b and the piston nut 21.

  Further, when the hydraulic shock absorber formed as described above is set to a single cylinder type, the piston side chamber R2 separated by the piston body 3 in the cylinder body 1 is not shown, but for example, a free piston It is good also as having an air chamber separated from piston side chamber R2.

  When the hydraulic shock absorber is set to a double cylinder type, although not shown, an outer cylinder is provided outside the cylinder body 1, and a reservoir is provided between the outer cylinder and the cylinder body 1. May communicate with the piston-side chamber R2 in the cylinder body 1.

  In the piston structure formed as described above, during the contraction operation in which the piston body 3 descends in the cylinder body 1, the hydraulic oil from the piston side chamber R2 passes through the outer passage 3a of the piston body 3 and the back surface. The valve 31 is opened to flow into the rod side chamber R1.

  In this piston structure, when the piston body 3 rises in the cylinder body 1, the hydraulic oil from the rod side chamber R <b> 1 passes through an inner passage (not shown) and opens the damping valve 32. It flows out to the piston side chamber R2, and at this time, a predetermined damping action is performed by the damping valve 32.

  As described above, at the time of the above-described contraction operation and extension operation, the piston ring 10 ensures so-called slidability between the piston body 3 and the cylinder body 1 and so-called between the piston body 3 and the cylinder body 1. Ensures sealing performance.

  As shown in FIGS. 2 and 3, the piston ring 10 is formed in an annular shape having an appropriate thickness so as to have a predetermined mechanical strength. In the illustrated case, the piston ring 10 does not have a joint at an arbitrary position in the circumferential direction. Formed.

  Incidentally, from the point of view of the present invention, the piston ring 10 may be formed in a cut type having an abutment a at an arbitrary position in the circumferential direction, as shown by a one-dot chain diagram in FIG.

  The piston ring 10 is made of a synthetic resin material such as polyphenylene sulfide resin, for example, by molding or the like, and is accommodated in an annular groove formed on the outer peripheral portion of the piston body 3.

  In the piston ring 10, the outer peripheral surface 11 is slidably contacted with the inner peripheral surface (not shown) of the cylinder body 1 while being accommodated in an annular groove formed in the outer peripheral side portion of the piston body 3. (Refer to FIG. 1), so-called leakage of hydraulic oil between the outer peripheral surface 11 of the piston ring 10 and the inner peripheral surface of the cylinder body 1 is prevented, that is, a sealing function is exhibited.

  On the other hand, the piston ring 10 has a plurality of grooves 12 that are provided on the outer peripheral surface 11 at an arbitrary interval in the circumferential direction and open and are opposed to the inner peripheral surface of the cylinder body 1.

  In the illustrated piston ring 10, the plurality of grooves 12 are formed in a direction along the axial direction of the cylinder body 1 and communicated with the rod side chamber R1 and the piston side chamber R2.

  For this reason, the groove 12 opened in the outer peripheral surface 11 of the piston ring 10 allows the hydraulic oil from the rod side chamber R1 and the piston side chamber R2 to enter when being accommodated in the cylinder body 1.

  The hydraulic oil that has entered the groove 12 forms a lubricating film between the outer peripheral surface 11 of the piston ring 10 and the inner peripheral surface of the cylinder body 1.

  It is preferable that the plurality of grooves 12 be arranged on the outer peripheral surface 11 of the piston ring 10 at an arbitrary interval in the circumferential direction. Preferably, the grooves 12 are provided at an equal interval, and the plurality of grooves 12 are provided at an equal interval. Thus, the circumferential sealability and slidability of the piston ring 10 with respect to the cylinder body 1 become uniform.

  In the piston ring 10, the plurality of grooves 12 communicate with the rod side chamber R <b> 1 and the piston side chamber R <b> 2, whereby the soaking of hydraulic oil into the groove 12 is not interrupted.

  Incidentally, although the plurality of grooves 12 are formed in the direction along the axial direction of the cylinder body 1 as described above, instead of this, as shown in FIG. A grid that is formed in a direction along the axial direction and has a lateral groove portion 12a that communicates with a groove 12 that is positioned in the circumferential direction between adjacent ones, that is, so-called vertical. It may be formed in a shape, or may be formed in a direction inclined with respect to the axial direction of the cylinder body 1 as shown in FIG.

  When the plurality of grooves 12 are formed in a cross shape that is continuous in the circumferential direction or in a lattice shape, the amount of hydraulic oil intrusion is larger than in the case where the grooves 12 are formed in a straight shape as shown in FIG. Thus, it is advantageous in reducing the sliding resistance between the piston ring 10 and the cylinder body 1.

  In this case, the contact area between the outer peripheral surface 11 of the piston ring 10 and the inner peripheral surface of the cylinder body 1 can be reduced. From this point also, the sliding between the piston ring 10 and the cylinder body 1 is possible. This is advantageous in reducing the dynamic resistance.

  Further, when the plurality of grooves 12 are formed in the inclined direction, when the number of grooves 12 is the same, compared to the case where the plurality of grooves 12 are formed in the vertical direction, This is advantageous in increasing the amount of hydraulic oil intrusion.

  In this case as well, an oil film is easily formed between the outer peripheral surface 11 of the piston ring 10 and the inner peripheral surface of the cylinder body 1, and also from this point, between the piston ring 10 and the cylinder body 1. This is advantageous in reducing the sliding resistance.

  In the above description, the plurality of grooves 12 are communicated with the rod-side chamber R1 and the piston-side chamber R2. However, when the present invention intends, that is, when hydraulic fluid enters the plurality of grooves 12. From this point of view, although not shown, the groove 12 may communicate with either the rod side chamber R1 or the piston side chamber R2.

  In this case, the length of the groove 12 is preferably at least half of the axial length of the piston ring 10, and when one groove 12 communicates with the rod side chamber R1, for example, It is preferable that the other adjacent groove 12 communicates with the opposite piston side chamber R2.

  The above description has been made from the state in which the plurality of grooves 12 are open to the outer peripheral surface 11, that is, the outer peripheral surface 11 of the piston ring 10 as viewed from the outside of the outer peripheral surface 11.

  On the other hand, the groove 12 has a so-called depth with respect to the opening on the outer peripheral surface 11, but the depth allows the hydraulic oil to enter the groove 12 and to allow the hydraulic oil to stay in the groove 12. That's enough.

  From this point of view, the depth of the groove 12 may be arbitrarily set. However, it is important that the depth of the groove 12 is not set so as to reduce the mechanical strength and the sealing performance of the piston ring 10 unnecessarily. .

  Therefore, as shown in the figure, the groove 12 is formed in the outer peripheral side portion 13 having the outer peripheral surface 11 in the piston ring 10, and the thickness of the outer peripheral side portion 13 is the radial direction of the piston ring 10. It is good to make it wall thickness, for example, 1/10 or less.

  And about the so-called cross-sectional shape of the groove 12, assuming that the depth of the groove 12 is the same, as long as it is formed so as to allow the hydraulic oil to enter, it has an arbitrary cross-sectional shape. May be formed.

  Of course, when the cross-sectional shape of the groove 12 is varied, the outer peripheral side portion is used to make the amount of hydraulic oil to be infiltrated the same as or different from that of the other groove 12 in any groove 12. As long as the groove 12 is formed, any one of the grooves 12 may have the same or different depth with respect to the other grooves 12.

  That is, the cross-sectional shape of the groove 12 may be rectangular as shown in FIG. 5 (A), for example, and may be U-shaped as shown in FIG. 5 (B). Further, as shown in FIG. 5C, it may be V-shaped, and further, although not shown, it may be any shape including other polygonal shapes.

  When the cross-sectional shape of the groove 12 is rectangular, the amount of hydraulic oil can be increased compared to the case where the cross-sectional shape of the groove 12 is U-shaped or V-shaped. When the surface shape is U-shaped or V-shaped, formation is easier than when the cross-sectional shape of the groove 12 is rectangular.

  That is, when the cross-sectional shape of the groove 12 is U-shaped, compared to the case where the cross-sectional shape of the groove 12 is rectangular, there are no so-called square corners on the inside, and the groove 12 When the cross-sectional shape of the groove 12 is V-shaped, the number of inner corners is reduced, and the groove 12 can be easily formed as compared with the case where the cross-sectional shape of the groove 12 is rectangular.

  And when the cross-sectional shape of the groove 12 is U-shaped or V-shaped, the amount of hydraulic oil intruding into the groove 12 is smaller than when the cross-sectional shape of the groove 12 is rectangular. Therefore, it can be said that the sealing performance is improved.

  On the other hand, the method of forming the groove 12 in the outer peripheral side portion 13 of the piston ring 10 is basically arbitrary, but in many cases, the piston ring 10 is made of a synthetic resin material, so It is formed at the same time as the mold used.

  That is, when the piston ring 10 is formed by molding, although not shown, the groove 12 may be formed by denting the outer peripheral surface 11 as engraved on the outer peripheral side portion 13 with linear ribs of the mold.

  However, from the point of view of the present invention, it does not prevent the grooves 12 from being formed by cutting the outer peripheral surface 13 of the molded piston ring 10 from the outer peripheral surface 11.

  And the upper end of the outer peripheral side part 13 in the piston ring 10 may be inclined so as to rise toward the center of the piston ring 10 as shown in FIG. Moreover, as shown to FIG.5 (E), you may finish so that it may curve toward the center of the piston ring 10 and it may rush up.

  When the upper end of the outer peripheral side portion 13 of the piston ring 10 is inclined or curved, it is easy to insert the piston ring 10, that is, the piston ring 10 wound around the piston body 3 into the cylinder body 1. To.

  Incidentally, although the upper end of the outer peripheral side portion 13 in the piston ring 10 is inclined or curved, although not shown, the lower end of the outer peripheral side portion 13 is similarly inclined or curved. Well, in this case, when the piston ring 10 is wound around the piston body 3, it is advantageous to eliminate a so-called top and bottom and prevent erroneous assembly.

  In addition, the upper and lower ends of the outer peripheral side portion 13 of the piston ring 10 are inclined and curved. In general, when this type of piston ring is commercialized, as a part of deburring, chamfering work is performed. Is the normal condition.

  This makes it possible to practice the above-described inclined finishing or curved finishing as a series of operations following this chamfering operation, which is advantageous in that it does not cause unnecessarily high product costs.

  In the piston ring 10 formed as described above, the plurality of grooves 12 that open to the outer peripheral surface 11 of the piston ring 10 infiltrate the hydraulic oil, and the hydraulic oil that enters the groove 12 is in the piston ring 10. A lubricating film is formed by leaching between the outer peripheral surface 11 and the other portion where the outer peripheral surface 11 faces, that is, the cylinder body 1 in the drawing.

  Therefore, even when the outer peripheral surface 11 of the piston ring 10 formed in a so-called smooth surface is in sliding contact with the inner peripheral surface of the opposing cylinder body 1, the outer peripheral surface 11 of the piston ring 10 is in contact. Since there is a lubricating film between the inner peripheral surface of the cylinder body 1 facing the piston ring 10, the operation when the piston ring 10, that is, the cylinder body 1 with which the piston ring 10 is in sliding contact, starts sliding is realized smoothly. Let

  In the piston structure having the piston body 3 around which the piston ring 10 is wound, that is, in the hydraulic shock absorber having the piston structure, when the rod body 2 enters and exits the cylinder body 1, Thus, the piston body 3 slides, and the rod side chamber R1 and the piston side chamber R2 in the cylinder body 1 expand and contract.

  When the rod side chamber R1 and the piston side chamber R2 expand and contract, the piston ring 10 slides on the inner periphery of the cylinder body 1 to prevent so-called leakage of hydraulic oil between the piston ring 10 and the cylinder body. Operation according to the setting of the valve 31 or the damping valve 32 is ensured.

  In the piston structure having the piston ring 10 as described above, the piston body 3, that is, the piston ring 10 does not form a lubricating film made of hydraulic oil therebetween, and is in sliding contact with the cylinder body 1. Reduce the resistance at the start of sliding.

  Therefore, in this piston structure, when the hydraulic shock absorber is reversed from the contracted state to the extended state or vice versa, the sliding resistance of the piston ring 10 with respect to the cylinder body 1 is reduced. The acceleration does not increase.

  As a result, according to the piston ring 10 and the piston structure having the piston ring 10 according to the present invention, in the hydraulic shock absorber mounted on the vehicle, it is possible to prevent the occurrence of an impact by not increasing the rod acceleration. Become.

  In the above description, the piston ring 10 according to the present invention has been described as being used for a hydraulic shock absorber. However, according to the configuration of the piston ring 10 according to the present invention, this is applied to a wear ring used for a fluid pressure cylinder. It can be said that it may be.

DESCRIPTION OF SYMBOLS 1 Cylinder body 2 Rod body 2a Tip part 2b Step part 3 Piston body 3a Outer passage 10 Piston ring 11 Outer peripheral surface 12 Groove 12a Lateral groove part 13 Outer peripheral side part 21 Piston nut 31 Back valve 32 Damping valve 33, 34 Valve stopper R1 Rod side chamber R2 piston side chamber a abutment

Claims (4)

In a piston ring that is housed in a cylinder body that contains hydraulic oil and is wound around a piston body that separates a rod side chamber and a piston side chamber in the cylinder body,
A circumferential outer peripheral surface that is in sliding contact with the inner peripheral surface of the cylinder body;
This outer peripheral surface has a plurality of grooves that are provided at arbitrary intervals in the circumferential direction and open to face the inner peripheral surface of the cylinder body,
The plurality of grooves are formed in a direction along the axial direction of the cylinder body or in a direction inclined with respect to the axial direction of the cylinder body and communicated with either the rod side chamber or the piston side chamber. Piston ring characterized by   The piston ring according to claim 1, wherein the plurality of grooves are formed at equal intervals in the circumferential direction on the outer peripheral surface.   2. The piston ring according to claim 1, wherein the plurality of grooves have a lateral groove portion positioned in the circumferential direction between adjacent ones, and are formed in a cross shape or a lattice shape continuous in the circumferential direction. A piston body that is housed in a cylinder body that stores hydraulic oil and separates the rod side chamber and the piston side chamber in the cylinder body, and an outer peripheral surface that is wound around the piston body and slides on the inner peripheral surface of the cylinder body. In the piston structure having a piston ring to contact,
4. The piston structure according to claim 1, wherein the piston ring is the piston ring according to claim 1, claim 2, or claim 3.

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